SLC3A2 and hypertrophic cardiomyopathy: Destabilization of the myosin energy-conserving SRX state is associated with contractile abnormalities, morphological and metabolic remodeling, and adverse clinical outcomes in patients with hypertrophic cardiomyopathy caused by mutations in the myosin heavy chain (53), myosin regulatory (50) and essential (54, 55) light chains.